rsnapbackup

#!/bin/bash
#
# A wrapper around rsnapshot that performs a config check prior to
# backing up and creates a 'dates' directory under the snapshot root
# with symlinks named after the date/time the backup completed.
#
set -e

#### Configurables ######

# default path if not supplied with -f
RSNAPSHOT_CONFIG=/etc/rsnapshot.conf

RSNAPSHOT_OPTS="-v"

# controls the names of the symlinks to the backups. See 'man date'
# for acceptable formats.
LINK_DATE_FORMAT="%F_%H-%M-%S"

#########################

BACKUP_LEVEL=
TIMESTAMP_PATH=
DRY_RUN=
SNAPSHOT_ROOT=

function usage()
{
    cat <<EOF
usage: $0 [options] -l <backuplevel>

OPTIONS:
   -h      Show this message
   -f      rsnapshot config file (optional)
   -l      backup level to pass to rsnapshot
   -n      Dry-run mode; run rsnapshot in test mode and skip making date symlinks (optional)
EOF
}


function die()
{
    echo $@ 1>&2
    exit 1
}

function warn()
{
    echo "WARN: $@" 1>&2
}


function make_indexes()
{
    # Find 'TIMESTAMP' files, read the contents, and create a symlink in a
    # YY-MM-DD_HH-MM-SS format to the folder in which the TIMESTAMP file
    # was found.
    #
    # Moves symlinks atomically by creating new links in 'dates.new' and
    # then moving using 'mv -Tf' to 'dates'
    local timestamp=
    (
	cd "$SNAPSHOT_ROOT"
	mkdir -p dates.new
	mkdir -p dates
	for file in $(find . -maxdepth 2 -name TIMESTAMP); do
	    timestamp=$(cat $file)
	    if [ -z "$timestamp" ]; then
		continue
	    fi
	    ( cd dates.new ; ln -s "../$(dirname $file)" $(date -d@$timestamp "+${LINK_DATE_FORMAT}") )
	done
	find ./dates -type l -delete
	mv dates.new/* dates
	cd - > /dev/null
    )
}

if [[ $EUID -ne 0 ]]; then
    die "Must be run as root"
fi

while getopts "hf:l:n" opt; do
    case $opt in
	h)
	    usage
	    exit 0
	    ;;
	f)
	    RSNAPSHOT_CONFIG="$OPTARG"
	    ;;
	l)
	    BACKUP_LEVEL=$OPTARG
	    ;;
	n)
	    DRY_RUN=1
	    ;;
	\?)
	    usage
	    exit 1
	    ;;
    esac
done

set -u

if [[ -z $BACKUP_LEVEL ]]; then
    die "backup level (-l <level>) is required"
fi

if [[ ! -z $DRY_RUN ]]; then
    RSNAPSHOT_OPTS="${RSNAPSHOT_OPTS} -t"
fi

if [[ ! -z $RSNAPSHOT_CONFIG ]]; then
    RSNAPSHOT_OPTS="${RSNAPSHOT_OPTS} -c $RSNAPSHOT_CONFIG"
fi

SNAPSHOT_ROOT=$(egrep '^snapshot_root\s+\/' "$RSNAPSHOT_CONFIG" | awk '{print $2}')
TIMESTAMP_PATH="${SNAPSHOT_ROOT}/${BACKUP_LEVEL}.0/TIMESTAMP"

if [[ -z "$SNAPSHOT_ROOT" ]]; then
    die "Could not parse snapshot_root setting in $RSNAPSHOT_CONFIG"
fi

rsnapshot configtest >/dev/null
rsnapshot $RSNAPSHOT_OPTS $BACKUP_LEVEL

if [[ -z $DRY_RUN ]]; then
    if [[ ! -e "$TIMESTAMP_PATH" ]]; then
	printf $(date +%s) > "$TIMESTAMP_PATH" || true
    fi
    make_indexes || warn "Failed to make indexes"
fi